User control in delegate control

Question

My question is regarding a delegate control called TopNavigationDataSource, normally when you create a delegate control you just define there some new properties etc.

But what if I want to deploy delegate control with user control? I did it this way:

  <Control Id="TopNavigationDataSource" Sequence="10" ControlSrc="~/_controltemplates/CustomNavUserControl.ascx">
  </Control>

In CustomNavUserControl.ascx i put following:

<asp:SiteMapDataSource ShowStartingNode="False" SiteMapProvider="MySiteMapProvider"
      id="topSiteMap" runat="server" StartingNodeUrl="sid:1002"/>

But when deploying it i get an error saying:

System.Web.HttpException: The DataSourceID of 'TopNavigationMenuV4' must be the ID of a control of type IHierarchicalDataSource. A control with ID 'topSiteMap' could not be found.

What is ofcourse not true as i have just above the delegate in master page the following:

    <SharePoint:AspMenu
  ID="TopNavigationMenuV4"
  Runat="server"
  EnableViewState="false"
  DataSourceID="topSiteMap"
  AccessKey="<%$Resources:wss,navigation_accesskey%>"
  UseSimpleRendering="true"
  UseSeparateCss="false"
  Orientation="Horizontal"
  StaticDisplayLevels="2"
  MaximumDynamicDisplayLevels="1"
  SkipLinkText=""
  CssClass="s4-tn" Width="16px" Height="16px"/>

What do I miss?

Answer 1

I think the error message states that your UserControl (CustomNavUserControl.ascx) does not implement IHierarchicalDataSource. So your code behind file (CustomNavUserControl.ascx.cs) of your UserControl must implement this interface.